The design of radial speaker horns, including such horns which are excited by speaker drive assemblies, has presented problems not amenable to ready solution. For example, the radial dispersion of sound energy emanating from a membrane of a drive assembly has been accomplished by disposing an element shaped for such dispersion in the path of the energy. However, the distance between the membrane and element and the lack of cooperating structure, conceived with considerations beyond the dispersion pattern in mind, have restricted the practically and desirabilty of such horns. Exemplary speaker horns of some interest in this regard are disclosed in Mattis U.S. Pat. No. 1,692,994, British Pat. No. 248,061, Blattner U.S. Pat. No. 1,996,743 and West German Pat. No. 868,454. Flynn U.S. Pat. No. 1,754,506 is also of some interest herein, as, to a lesser degree, are British Pat. Nos. 566,398 and 500,493.
Thus, designs for radial horns generally focus on achieving a desired radial pattern with attention to other matters, such as intensity considerations, of subsidiary concern. For example, in a number of conventional designs the radial horn includes a conical section flaring outwardly and a relatively flat (or perhaps convex) surface structure positioned opposite the flaring structure to cooperate in determining the radial pattern by deflecting sound from the conical section. This type of structure, with a membrane for a drive assembly at the small cone end, typically results in the sound energy emanating from the membrane acting upon a relatively low pressure volume which in turn acts upon a relatively high pressure volume starting at the shortest radial distance between the conical section and the surface. This sort of arrangement, normally involving a path for the sound energy which contracts at one or more points, generally sacrifices gain or amplification possibilities for other concerns.
The use of sound energy emanating from the convex side of a membrane in a drive assembly offers certain advantages which have made this type of structure conventional in a variety of applications. Since, however, particularly for high frequencies of the order of 20 kilohertz, the difference in phase of the energy emanating from near the center of the membrane may become significant with respect to that emanating from near the edges of the membrane, it has also become the practice in many applications to employ phase correctors with such membranes. These phase correctors typically include an element having a concave surface opposite the convex membrane and further having an array of holes through the surface near the periphery. In this manner, energy from the center of the membrane reflects off the non-apertured concave portion of the phase corrector surface and travels generally along the surface to reach the holes. This in effect delays or lengthens the path of such sound energy to compensate for the difference in path length between the sound from near the edges of the membrane and the sound from near the center of the membrane.
In the type of radial horn described above, such a phase corrector element would typically be placed opposite the membrane at the small or input end of the conical section.
The present invention addresses the achievement of a desired radial dispersion pattern without sacrificing amplification considerations. Further, in providing structure for addressing that goal, it in addition addresses the need for phase correction.